ES2885753T3 - Security valve - Google Patents

Abstract

Gas supply apparatus comprising a combination of: a gas flow meter (11) with a body and a rotary control knob (15) for controlling the rate of gas flow through the gas flow meter; and a breathing gas safety valve (56) for use in medical apparatus for supplying a gas capable of combustion or supporting combustion; said valve being operable to shut off the gas flow path from the source thereof in the event of a fire, said breathing gas safety valve comprising a body (57), a valve member with a valve head (65) elastically displaced toward a closed valve position and a fusible retainer (73) holding the valve member, against displacement, in an open valve position, the valve body (57) defining a fluid flow path, between an outlet and said valve head (65), into which an elongated link member (66) extends from the valve head (65) to a bracket (67) that engages the fusible retainer (73), a nozzle ( 58) connectable to a supply line for supplying the gas to an end user and connecting means operable to releasably connect the valve body (57) directly to the gas flow meter body in line with the gas supply path of the caude gas alimeter.

Description

DESCRIPTION

Security valve

This invention relates generally to apparatus and instruments for handling a gas capable of combustion or supporting combustion, and incorporating a safety valve unit, and relates specifically, but not exclusively, to such apparatus and instruments used in association with ventilators for supplying oxygen to patients both in hospitals, by emergency services, and more particularly in the domestic environment where awareness of the danger resulting from the use of an oxygen-enriched environment may not be as readily appreciated.

The provision of supplemental oxygen to patients suffering from acute respiratory disorders is becoming widespread. The supply of said oxygen to the patient is usually effected through an interface such as a nasal cannula, a face mask or even an endotracheal tube. Oxygen is supplied to the interface unit via flexible plastic tubing from an oxygen source.

Oxygen can be supplied in three ways, namely in compressed form in cylinders, from concentrators that draw oxygen from the atmosphere, or as liquid oxygen in a Dewar flask. Such sources are typically attached via a plastic line to a face mask, nasal cannula, or endotracheal tube.

Clinical experience and experience in the home have established that the risk of fire when using such an oxygen supply apparatus is particularly significant, since the exposure of the apparatus to a combustion ignition event, such as an electrical short, a Faulty cooking element, open flames such as candles, matches, or cigarettes can ignite with a flame that starts as an external fire sustained by an oxygen leak from the supply appliance, and then moves into the tube and migrates rapidly upstream toward the oxygen source. The risk of fire resulting from the use of oxygen supply devices is aggravated in the domestic environment, where such therapy is used more and more frequently, because the use of oxygen is not supervised by health workers, and even the presence of smoke detectors Mandatory smoke, fire alarms and other similar safety equipment cannot mitigate the risks due to the rapidity of the conflagration once it is activated. The risk of catastrophic fires, especially due to careless use of such a device, is much greater in the case of patients who smoke, as there is a temptation for the patient to discard the oxygen supply mask or cannula, leaving it lying in the the vicinity. while smoking a cigarette. Most oxygen delivery devices are configured to deliver oxygen continuously at a rate determined by the patient's needs, and removal of the delivery interface from the patient's airway does not cause oxygen delivery to cease. In such circumstances, an oxygen-enriched atmosphere can build up around the patient, coating any bedding or decoration materials and setting the scene for a catastrophic conflagration upon ignition by the slightest spark.

Therefore, there is a need for apparatus and/or methods to prevent or prevent a fire from occurring as a result of an ignited material in an oxygen-enriched environment, in the vicinity of a patient wearing such a respirator.

In addition, the patient interface component of respiratory equipment, such as face masks and nasal cannulae, is often disposable, and therefore there is a strong incentive for any safety equipment associated with it to be inexpensive and easy to install. There is also a requirement that all safety valve units be formed so that they do not weigh down on a supply line and pull on connections causing them to loosen, and also so that a safety valve unit connected near a mask facial or a cannula does not cause undue discomfort to the patient due to its weight. Although it is known how to provide safety valves for insertion into a gas supply line, the present invention seeks to address the problem by devising a way in which a safety valve can be effectively and easily incorporated into a system component while remaining accessible for verification and easy replacement.

Patent Document Number GB 2417425 describes an in-line safety valve comprising a shuttle. The safety valve shuttle has a sealing ring. The valve includes a spring that biases the shuttle into a "valve closed" position, and also includes a fusible stop, which prevents the valve from closing. In the event of a fire, the stopper fuses, allowing the spring to close the valve which can be moved inside a hollow body. The valve body has elongated stems that end in nipples, to which a tube can be connected.

Patent Document Number GB 2418239 describes a coupling for connecting two lengths of hose. The coupling includes a thermally activated safety valve, pushed in one direction to shut off gas flow, but held open by a sliding sleeve, held in position by a thermally activatable element. If the hose catches fire, the flame traveling inside the hose causes the heat-activatable element to melt, allowing movement of the sliding sleeve and closing of the valve.

Accordingly, the present invention provides a gas supply apparatus as claimed in claim 1.

Accordingly, the present invention may assist in providing an apparatus for use in supplying a gas capable of combustion or supporting combustion by incorporating a safety valve unit for shutting off the gas flow path from the gas source in case of fire

The elongate link member may be a generally flat or lamellar element. Alternatively, the elongate member may take the form of a substantially cylindrical element or a tapered cylindrical element. The elongate link member may be integral with the valve head or alternatively may be a separate element.

The valve head may further include a sealing member. The sealing member and the valve head may be arranged to cooperate such that the sealing member seals against the wall of the fluid flow passage when the valve member is in the closed position. The sealing member may, for example, take the form of a substantially spherical ball member, and the valve head may be shaped to seat the sealing member.

Alternatively, the valve head may have an annular recess and an annular sealing member disposed therein to form a seal between the valve head and the wall of the fluid flow passage when the valve member is in the valve head. valve closed position.

At least a portion of the valve head surface may be formed of a suitable material to form a seal between the valve head and the wall of the fluid flow passage when the valve member is in the off position. valve closure. The head assembly itself may be formed of said material. Alternatively, the sealing member may be formed of a suitable material to form a seal against the wall of the fluid flow passage when the valve member is in the valve closing position.

The support may comprise at least one lateral protrusion. However, the support may comprise two or more lateral protrusions, which are preferably diametrically opposite positions across a plane of symmetry of the elongated link member.

The fusible retainer may be in the form of an inwardly directed annular flange arranged to retain the valve member carrier within the hollow body. The fusible retainer can be formed from a heat sensitive material, which can be selected from thermoplastic materials, solder materials and waxes. In a preferred embodiment, the fusible retainer is formed from a thermoplastic material, such as, for example, polyvinyl chloride (PVC).

The valve member may be elastically biased by a coiled compression spring mounted within the hollow body and compressed between an internal annular rim provided by the valve body and an annular shoulder on the valve head.

In another aspect, the present invention provides an apparatus in which the valve support comprises at least one lateral protrusion.

In such valves, the means for securing the valve body to a component part or ancillary unit associated with the gas supply apparatus comprises a hollow tubular spout for insertion into an opening in the body of said component or ancillary unit, securing means gas-tight sealing on said spout and means for retaining the spout in position within the opening in said body. Said retaining means may comprise one or more lateral protrusions to form a bayonet-type coupling. Alternatively, said retaining means comprise a threaded portion for engaging a corresponding thread in the opening.

The present invention also includes a respiratory support apparatus incorporating said safety valve.

By way of example only, embodiments of the present invention are described in connection with the accompanying drawings, in which:

Figure 1 is a front view of a flowmeter incorporating a safety valve unit;

Figure 2 is a perspective view of a nasal cannula delivery respiratory support system incorporating a safety valve;

Figure 3 is a perspective view of a face mask patient interface device for a respiratory support system incorporating a safety valve;

Figure 4 is a perspective view of a safety valve adapted to fit into a component part or auxiliary unit of the gas supply apparatus;

Figure 5 is a perspective view of an alternative form of safety valve unit adapted to fit into a component part or auxiliary unit of the gas supply apparatus;

Figure 6 is an axial section through another safety valve unit; Y

Figures 7, 8 and 9 are perspective views of alternative forms of safety valve unit, adapted to be fitted to a component part or auxiliary unit of the gas supply apparatus; Y

Figure 10 is an exploded perspective view of the safety valve unit of Figure 8.

Referring now to the drawings and in particular to Figure 1, there is shown a flow meter generally indicated 11, intended to form part of a gas supply apparatus adapted as a respiratory support system to supply oxygen from a source (not shown). which is connected by a flexible line generally indicated as 12 to an inlet nozzle 13 projecting from a generally cylindrical flow meter body 14.

Projecting from the body 14 of the flow meter is a control knob 15 which can be turned to control the rate of gas flow through the unit. Projecting upwardly from the body 14 is a hollow cylindrical flow indicator body 16 having a transparent window 17 through which the interior passage of the indicator body 16 may be observed. Within this passage is a lightweight ball indicated generally with 18. In the use of the flow indicator, the gas arriving at the inlet 13 is passed through the interior passage 17 inside the indicator body 16, carrying with it the light ball 18. The gas is then passed through a passage (not shown) back to the body 14 from where it exits through an outlet generally indicated 19. Outlet 19 is formed as a safety valve 20 having an outlet nipple 21 to which a flexible line indicated usually with 22 at the supply outlet of the gas supply apparatus, which may, in the case of a respiratory support apparatus, be a nasal cannula device as shown in Figure 2, or a ma facial mask as shown in Figure 3.

Safety valve 20 is one that has a heat sensitive element located in the connector nozzle 21 which, if the patient starts a fire at the supply end of the apparatus, for example by smoking, senses the temperature rise as the flame front approaches along line 22 and merges allowing a valve element within unit 20 to close, thus isolating flow meter 11 and the rest of the supply apparatus, including, especially, the source of combustion support gas (usually oxygen) for the fire.

Figure 2 illustrates the supply end of the apparatus, a part of which is shown in Figure 1, comprising two parallel flexible lines 23, 24 leading from the single line 22 (by means of a branching or twinning device (not shown)) which are held together by means of a sleeve 25. The end portions 26, 27 of the lines 23, 24 are formed into a loop and connected, via respective safety valves 28, 29, to a nasal cannula 30 of known type having two parallel outlet nozzles 31,32 which, in use, are inserted into the respective nostrils of a user. Safety valves 28, 29, like valve 20 in Figure 1, act to detect a rise in temperature indicating that a fire has started, and close to isolate the rest of the system from the source of the fire. By placing the valves 28, 29 close to the nasal cannula 30, a rapid response to the start of a fire can be achieved. In an alternative embodiment, not shown, these valves may be located downstream of lines 26, 27 or in sections 23, 24 of lines upstream of sleeve 25.

In Figure 3, the line 22 is shown connected by a safety valve 33 to a face mask 34 which has a normal configuration with a padded edge 35 and an elastic retention band 36.

As with safety valves 28, 29 in Figure 2, valve 33 senses a rise in temperature indicating a fire may have started and shuts off communication with line 22. This is particularly important in circumstances where , for example, respiratory support apparatus of which the face mask or nasal cannula (in Figure 2) are used at home without close clinical supervision, as a forgetful patient may remove the mask or cannula and place it on the bed or chair next to him or her, and then engage in any activity, such as smoking, lighting candles, or the like, that could ignite the gas escaping from the open end of the supply device. It will be appreciated that, in most cases, the oxygen supplied through line 22 is emitted at a metered rate suitable to the patient during inhalation, but continues during exhalation at the same rate so that the atmosphere around the The patient is converted to enriched oxygen while the apparatus is in use, and of course if the supply outlet were to be placed away from the patient, the gas flow continues unabated unless shut off by a main control valve.

Safety valves can be adapted to be installed directly on the body of a pressure regulator, flow meter or other element of a gas supply system. In Figure 4, a safety valve, generally indicated 37, is made up of two parts, 38, 39, which can be interlocked, for example by screwing. Part 38 substantially comprises a hollow cylindrical spigot having an open end or mouth 40 with a circumferential annular groove in its vicinity, which houses an O-ring 41. A main part 42 is threaded, and a radial knob 43 is provided at the end. away from the port 40 to help not only secure the safety valve 37 in position on the component it is intended to engage, but also to help connect the second component 39 to it. This second component 39 comprises a generally cylindrical body portion 44 with two radially opposite projecting lugs 45, 46 serving as lugs, and having a hollow nozzle 47 in axial alignment with the hollow spigot. A typical internal safety valve construction will be described in more detail in connection with Figure 6.

Turning now to Figure 5, one arrangement comprises a main body portion 48 from which protrudes a nozzle 49 corresponding in function to nozzle 47 in the Figure 4 embodiment.

Projecting radially from body 48 are two radial projections 50, 51 which form part of a generally elongated enlargement of body 48 and serve as a handle for mounting and removing the safety valve. Projecting axially in the opposite direction from the nozzle 49 is a hollow tubular spout 52 which, as in the Figure 4 embodiment, has an open spout 53 and an O-ring 54 housed in an annual circumferential groove adjacent the end of the open spout. 53.

Projecting laterally from the cylindrical body of the spigot 52 is a radial boss 55 which, when the valve is mounted on a component of the gas supply system, fits within an axial slot and, as the body 48 is rotated by means of the lugs 50, 51 forms a bayonet-type coupling within the apparatus.

Turning now to Figure 6, an exemplary interior structure for the safety valve is shown. It should be understood, however, that the internal structure of the safety valves referred to in Figures 1 to 5 may not necessarily be identical to this and that other configurations of safety valves may be used, for example, that known from prior patent application number GB 0624524.5 owned by applicants.

In Figure 6 it can be seen that the valve shown has a body 56 with a cylindrical main body portion 57 from which a nozzle 58 protrudes in one direction and a hollow spout 59 in the other. The open end of the spigot 59 receives an annular cap 60 with a central opening 61 defining an annular shoulder 62 whose function is to engage one end of a spring 63 which biases a valve plug 64 towards a valve closure position as will be explained. in more detail below.

The opposite end of spring 63 acts on valve plug member 64 which is mounted within valve body 57. Valve plug member 64 comprises a head 65 integrally formed with an elongated link member 66 extending it extends through the nozzle 56 and terminates in a support 67. The elongated link member 66 is generally flat while the head 65 has a conical tapered neck portion 68, configured to correspond to an annular valve seat 69 formed in the inner surface of body 57. Head 65 has an annular recess 70 defined between neck portion 68 and a shoulder 71.

The end of the spring 63 bears against the shoulder 71 and the recess 70 houses an elastic sealing O-ring 72, the function of which is described below.

Support 67 of elongate link member 66 bears against a fusible retaining member in the form of a collar 73 which is mounted on the outlet end of nozzle 58. Retaining collar 73 has a sleeve portion 74 and a sleeve portion 74 . end cap 75. Sleeve portion 74 fits within the open end of the nozzle and has lugs which form a snap fit with the rim recess on the interior surface of the body. Annular end portion 75 provides a radially inwardly extending rim or rim 76 against which support 67 abuts.

Retaining collar 73 is formed of a material that is sensitive to heat and softens or melts at temperatures that may be caused by flashback and/or ignition of a gas. At the same time, the material must have sufficient strength so that, in use, it retains its structural integrity within the outlet end of the nozzle section against the compressive force of spring 63 acting on it via the valve member. 65, link 66 and support 67. Suitable materials are some thermoplastics such as, for example, polyvinyl chloride (PVC), and materials such as waxes and lead-free solders.

The inner surface of body 57 defines annular shoulder 69 which is generally frustoconical in shape. The tapered annular shoulder is arranged to be engaged by the O-ring 72 in the event of the collar 73 melting due to its exposure to excessive heat, for example, due to a fire or explosion in its vicinity.

In use, the safety valve is placed between the circuit of a pressurized gas supply such as is commonly used in the home for those who need oxygen to help the patient breathe, and a respiratory support device, such as a mask or a nasal cannula. The gas supply may be in the form of an oxygen cylinder providing oxygen for enrichment of the normal oxygen input by mixing it with ambient air, or it may be in the form of a source of oxygen-enriched air, both under pressure. The patient supply pressure is regulated by suitable pressure regulators (not shown). The valve unit, in use, is positioned so that, should oxygen or oxygen-enriched air ignite, this supply can be rapidly shut off. To this end, if the collar 73 softens in the event of a temperature increase to such an extent that it becomes weak enough not to resist the force of the spring 63, the spring will overcome its resistance, thus moving the valve member immediately to press the sealing ring 72 against the annular shoulder 69, thus closing the valve unit.

Figures 7, 8 and 9 share several features with the relief valve unit shapes shown in Figures 4 and 5. The relief valve unit of Figure 7 is an alternative version of the relief valve unit. Figure 5 safety valve unit and Figure 8 safety valve unit is an alternative version of the safety valve unit of Figure 4. Therefore, the same numbering conventions have been used in relation to these figures where appropriate. In Figure 9, the safety valve, generally indicated 37, is made up of two parts, 38, 39, which can be joined, for example, by screwing. Portion 38 substantially comprises a hollow cylindrical portion with an open end 40 or mouth. Second component 39 comprises a generally frustoconical body portion 44 and has a hollow nozzle 47 in axial alignment with hollow cylindrical portion 38.

Figure 10 is an exploded perspective view of the safety valve unit of Figure 8. It will be appreciated that it illustrates an alternative exemplary interior structure for the safety valve.

In Figure 10 it can be seen that the valve shown has a body 56 with a cylindrical main body portion 57 from which a nozzle 58 protrudes in one direction and a hollow spout 59 in the other. As described in connection with Figure 6, the open end of the spigot 59 receives an annular cap 60 with a central opening defining an annular shoulder (not shown) whose function is to engage one end of a spring 63 biasing a. valve plug 64 toward a valve-closing position as will be explained in more detail below.

The opposite end of spring 63 acts on valve plug member 64 which is mounted within valve body 57. Valve plug member 64 comprises a head portion 65 integrally formed with an elongate substantially cylindrical conical link member 66 which , in use, extends through the nozzle 56 and terminates in a support portion 67. The elongate link member 66 is generally cylindrical and tapered. The head portion includes a cup-shaped seat (not shown) shaped to receive a substantially spherical ball sealing element 77.

The end of spring 63 bears against sealing element 77, the function of which is described below.

The support 67 of the elongated link member 66 bears against a fusible retaining member in the form of a collar (not shown) which is mounted on the outlet end of the nozzle 58. The retaining collar has a sleeve portion and a annular end portion as described in relation to Figure 6. The sleeve portion fits within the open end of the nozzle and has lugs which form a snap fit with an edge recess on the inner surface of the body. Annular end portion 75 provides a radially inwardly extending rim or rim against which support 67 abuts.

The retaining collar is made of a material that is sensitive to heat and softens or melts at temperatures that can be caused by flashback and/or ignition of a gas. At the same time, the material must have sufficient strength so that, in use, it retains its structural integrity within the outlet end of the nozzle section against the compressive force of spring 63 acting on it via the valve member. 65, link 66 and support 67. Suitable materials are some thermoplastics such as, for example, polyvinyl chloride (PVC), and materials such as waxes and lead-free solders.

The inner surface of body 57 defines annular shoulder 69 which is generally hemispherical in shape. The tapered annular rim is arranged to be engaged by the sealing element 77 in the event of the collar melting, due to its exposure to excessive heat, for example, due to a fire or explosion in its vicinity.

Claims (11)

1. Gas supply apparatus comprising a combination of: a gas flow meter (11) with a body and a rotary control knob (15) for controlling the rate of gas flow through the gas flow meter; and a breathing gas safety valve (56) for use in medical apparatus for supplying a gas capable of combustion or supporting combustion; said valve being operable to shut off the gas flow path from the source thereof in the event of a fire, said breathing gas safety valve comprising a body (57), a valve member with a valve head (65) elastically displaced toward a closed valve position and a fusible retainer (73) holding the valve member, against displacement, in an open valve position, the valve body (57) defining a fluid flow path, between an outlet and said valve head (65), into which an elongated link member (66) extends from the valve head (65) to a bracket (67) that engages the fusible retainer (73), a nozzle ( 58) connectable to a supply line for supplying the gas to an end user and connecting means operable to releasably connect the valve body (57) directly to the gas flow meter body in line with the gas supply path of the caude gas alimeter. 2. Gas supply apparatus according to Claim 1, in which the connection means comprise a hollow tubular spigot (59) for insertion into an opening in the body of the gas flow meter, gas-tight sealing means on said spigot and means for retaining the spout in position within the opening in the body of the gas flow meter. 3. Gas supply apparatus according to Claim 1 or Claim 2, wherein said connecting means comprises one or more lateral protrusions (55) to form a bayonet-type coupling. 4. Gas supply apparatus according to Claim 2, wherein said connecting means comprises a threaded portion (38) for engaging a corresponding thread in the opening. 5. Gas supply apparatus according to Claim 2, wherein said gas-tight sealing means comprises an elastic O-ring fitted in a circumferential groove surrounding the mouth of the spigot. 6. Gas supply apparatus according to any one of Claims 1 to 5, wherein a heat sensitive fusible element (73) is located at the outlet end of said nozzle (58). Gas supply apparatus according to any preceding claim, wherein said fluid flow path is defined between the elongate link member (66) and a wall of said fluid flow passage. Gas supply apparatus according to any preceding claim, wherein the valve head (65) is integrally formed with said elongated link member (66). Gas supply apparatus according to any preceding claim, wherein the valve head (65) has an annular recess and an annular sealing element (72) disposed therein to form a seal between the valve head valve and a wall of the fluid flow passage when the valve member is in said valve closing position. Gas supply apparatus according to any preceding claim, wherein at least a portion of the valve head surface (65) is formed of a sealing material. Gas supply apparatus according to any preceding claim, in which the support (67) comprises at least one lateral protrusion.